In today's society, use of modem information-processing machines and entertainment electronic products (including computers, fax machines, modems, printers, monitors, scanners, telephone answer machines, wireless telephones, copy machines, VCRs, stereos, microwave machines, etc.) has nearly become a routine practice for everyone. Not only are billion units of such electronic products in service, but more and more new units will be manufactured and sold. As a result, power or energy waste can be accumulated to an alarming amount even if each unit is inefficient in power conserving for just one watt.
Inefficiency in power utilization can be seen in any electronic products that require line-operated power supplies. In the category of information-processing products, for example, a typical fax machine has to consume roughly 10 watts of power in order to maintain its standby state for detecting an incoming call of facsimile information.
Recently, a great deal of effort has been made to conserve power usage in information-processing apparatuses, for example, U.S. Pat. Nos. 5,491,721 and 5,530,879 dealing with modems, and U.S. Pat. No. 5,588,054 dealing with a computer system. The prior arts basically improve power utilization after AC power is converted to regulated DC power through utilizing a power management processor to place an information-processing device selectively between a normal state and a standby state. Improvement of a modem alone has no ability to enable its associated power-supply unit to operate more efficiently. On the other hand, the power-supply unit of U.S. Pat. No. 5,530,879 remains inefficient and has to consume about 5 watts for maintaining a 486-based computer in a suspended state. The other disadvantage of the power-supply unit is that it can at best place its line-operated monitor in a standby state, which again incurs energy waste even if the monitor is redundantly equipped with energy-conserving hardware.
Further, the applicant believes that a higher amount of energy waste is inevitable for a 586-based, Pentium.RTM.-based, or other high-performance computer system because the cooling fan attached to a newer, power-hungry microprocessor and the cooling fan enclosed in its power-supply unit will always keep rotating and will thus incur additional energy waste, even if a power-supply unit is designed in accordance with U.S. Pat. Nos. 5,530,879, 5,491,721 and 5,588,054.
On the other hand, U.S. Pat. No. 5,410,713 describes a computer power system having a keep alive power supply, a switchable power supply, and a power management processor, wherein both the keep alive power supply and the switchable power supply are obtained from converting an external AC-power source to regulated DC power. As detailed in its claims, the prior art specifically directs that the output of the switchable power supply be coupled to supply power to a computer. Consequently, similar to the other prior arts mentioned hereinabove, it emphasizes the energy conservation of the host computer rather the computer power system itself because it does not recognize the fact that consistent rotating of the cooling fan of the computer power system also incurs substantial energy waste even when its host computer enters a standby state.
Also well known in the conventional power-conservation practice is a method of requesting a business machine to enter a standby state through software. For instance, an NEC SuperScript 660 laser printer can be automatically powered down from 400 watts to 15 watts through its software program. Many other information-processing machines need to continuously maintain such a standby state in order to render a computer system or a fax machine capable of receiving facsimile information through a telephone line. Even though it is only 15 watts per standby machine, energy waste associated with the standby state can accumulate to an unbelievable amount in view of the mass market of electronic products placed in service.
In the category of entertainment electronics, a VCR needs to maintain its standby state in order to run its timer and to retain and execute a program preset by a user. Likewise, modern television sets, Hi-Fi stereos, microwave machines, telephone answer machines, wireless telephone machines, and alarm radios all need to continuously maintain their respective standby states in order to be readily operable or to be responsive to a remote control signal. For achieving the convenience of these features, each of the entertainment electronic products has being equipped with a power-supply unit capable of switching between two states manually or automatically. However, the convenience is obtained at the cost of wasting AC power. In addition to energy waste, the standby state of the conventional practice causes unpleasant noise (generated from a cooling fan, for instance) and shortens the life spans of electronic products.
The power system of conventional computer provides no immediate solution to the energy waste associated with the two-state power system of the entertainment electronics. Nor is the two-state power system of the entertainment electronics capable of resolving the energy waste of information-processing devices.
It becomes evident that the conventional line-operated power system utilized to power the modern information-processing and entertainment electronic products is inefficient in power conservation; an enormous amount of energy has been and will be inevitably wasted if the power systems of these products are continuously manufactured in accordance with the conventional practice. Consequently, there is an urgent need to design a novel power-supply system for efficiently conserving power and energy usage in the mass market of electronic products. This can lead to an enormous amount of energy savings even if each of the power-supply systems saves only one single watt.